As an option to mitigate the increasing level of greenhouse gas emission, a number of Carbon Capture and Storage (CCS) testing and pilot projects have been brought up all over the world. In general, there are three types of CO2 storage formations, such as deep saline aquifers, depleted oil and gas reservoirs, and un-mineable coal seams. This study is focused on the deep saline aquifer which has the largest potential for CO2 storage. There are a lot of uncertainties associated with this type of storage, such as storage capacity, geomechanical properties, and sealing behaviour of the caprock. Pressure (and temperature) changes during CO2 injection and storage can have significant impact on the stress and strain field and may cause relevant geomechanical problems. This paper shows a case study of a synthetic saline aquifer storage site, where a 15-year injection at a rate of 15 MT/year was simulated. Sealing performance and leakage risk were evaluated. A number of sensitivity studies were conducted to analyse the impacts of different rock properties on CO2 leakage potentials. Coupled flow simulation and geomechanical modeling was performed to monitor stress-strain evolutions and to predict failure potentials in response to pressure changes during CO2 injection and storage. The findings show that CO2 leakage is most sensitive to caprock permeability. Other factors such as reservoir properties, boundary conditions, and perforation intervals also have certain degree of influence on the leakage. During the 15-year injection, there is no significant risk of potential failure; however, this may happen in local area due to formation heterogeneity.

Brook, M., K. Shaw, C. Vincent, and S. Holloway, 2003, GESTCO case study 2a-1: storage potential of the Bunter Sandstone in the UK sector of the Southern North Sea and the adjacent onshore area of eastern England.